Method of preparing roll surfaces



United States Patent No Drawing. Filed Apr. 10, 1963, Ser. No. 271,895 4 Claims. (Cl. 51289) This invention relates to the preparation of roll surfaces and more particularly to a method of preparing the surfaces of work rolls which are used in roll bonding a strip of aluminum between two strips of stainless steel.

In the manufacture of a composite strip of aluminum bonded between strips of stainless steel which is particularly adapted for use in making cookware, it is necessary to keep to a minimum the amount of reduction in thickness of the stainless steel to prevent its work hardening. It is necessary to keep this work hardening to a minimum because it is not feasible to heat treat the composite structure to remove this work hardening from the stainless steel since the temperatures required are so high that they would cause either fusion of the aluminum strip or at least render it dead soft and unusable. Hence, the composite strip must emerge from the roll bonding operation having the physical properties desired without the necessity of further high temperature heat treatments.

It is therefore a principal object of this invention to provide a method of preparing the surface of work rolls which will minimize the amount of reduction of the stainless steel strips in the roll bonding of stainless steel and aluminum.

A related object of this invention is the provision of a method of preparing the surface of work rolls for use in roll bonding of stainless steel and aluminum strips which will provide a composite finished strip having a bright surface finish free of directional lines and which will maintain the reduction in thickness of the stainless steel to a minimum.

These and other objects together with the fuller understanding of this invention will become apparent from the following description when taken in conjunction with the appended claims.

According to this invention, a steel work roll which is to be refinished to provide a desirable surface for a roll bonding operation is mounted in a conventional roll grinding machine which is adapted to rotate the roll about its axis of rotation. As the roll is rotated the surface is first prepared by grinding it with a grinding wheel rotating about an axis parallel to the axis of rotation of the roll.

The grinding wheel is moved slowly along the surface of the roll as both are being rotated until all previous marks and patterns have been removed in a conventional manner. The grit size of this grinding wheel should be from about 80 mesh to about 2600 mesh. The size that is selected depends upon the surface condition of the roll before the grinding is commenced. It has been found that in most instances excellent results are obtained by using a grinding wheel of about l50 mesh grit size; hence, for a standard, this size is preferred. The roll is then given a finish grind with an abrasive block having a grit size of from about -600 mesh to about -800 mesh. This finish grind is accomplished by biasing the block 3,253,370 Patented May 31, 1966 ice against the surface of the roll and oscillating it rapidly on a path parallel to the axis of the rotation of the roll and also moving it slowly along the length of the roll as the roll is rotating. This will provide the desired finish and remove any directionality marks imparted by the grinding wheel. These directionality marks imparted by the grinding wheel extend circumferentially or spirally around the roll and if they are not removed, will appear as longitudinal lines on the surface of the strip produced. Although the grit size of this block may vary between 600 and -800 mesh, the 800 mesh is preferred since it will result in a surface finish on the surface of the strip brighter than that of a -60O mesh grit.

The surface resulting on a roll refinished according to this invention will have a uniform roughness or mat-finish of from about 4 to about 10 microinches R.M.S. with the surface being free of directionality or grinding patterns. This roughness of between 4 and 10 microinches R.M.S. is required to effectively roll bond aluminum strip between strips of stainless steel without excessively work hardening the stainless steel. If the roll is any smoother than about 4 microinches R.M.S., the stainless steel strips will tend to slip which will cause a substantial reduction in their thickness resulting in an undesirable amount of work hardening of the stainless steel. If, on the other hand, the surface of the rolls is rougher than about 10 microinches R.M.S., a very satisfactory bond will be obtained without an undesirable amount of work hardening of the stainless steel, but the surfaces of the stainless steel will have such a dull appearance that the subsequent polishing will be required to obtain the required surface finish. Although this can be readily accomplished, it is an additional operation which adds to the expense of the material, and for the sake of economy, should be avoided.

Although one embodiment of this invention has been shown, various adaptations and modifications may be made without departing from the spirit and scope of the appended claims.

We claim:

1. The method of refinishing the surface of a steel work roll while the roll is being rotated about its axis of rotation comprising, the steps of grinding the surface of said roll with an abrasive wheel having a grit size of from about mesh to about -8()0 mesh, and thereafter finishing the surface of the roll with an abrasive block held against the surface of the roll and oscillating on a path parallel to the axis of rotation of the roll, the abrasive of said block having a grit size of from about 600 mesh to about -800 mesh, whereby to produce a roll surface free of directionality and characterized by a roughness of from about 4 to about 10 microinches R.M.S.

2. The method of refinishing the surface of a steel work roll while the roll is being rotated about its axis of rotation comprising, the steps of grinding the surface of said roll with an abrasive wheel having a grit size of from 80 mesh to about -800 mesh, and thereafter finishing the surface of the roll with an abrasive block held against the surface of the roll and oscillating on a path parallel to the axis of rotation of the roll, the abrasive of said block having a grit size of about -800 mesh, whereby to produce a roll surface free of directionality and characterized by a roughness of from about 4 to about 10 microinches R.M.S.

3. The method of refinishing the surface of a steel work roll while the roll is being rotated about its axis of rotation comprising, the steps of grinding the surface of said roll with an abrasive wheel having a grit size of about 150 mesh, and thereafter finishing the surface of the roll with an abrasive block held against the surface of the roll and oscillating on a path parallel to the axis of rotation of the roll, the abrasive of said block having a grit size of from about 600 mesh to about -800 mesh, whereby to produce a roll surface free of directionality and characterized by a roughness of from about 4 to about 10 microinches R.M.S.

4. The method of refinishing the surface of a steel work roll while the roll is being rotated about its axis of rotation comprising, the steps of grinding the surface of said roll with an abrasive wheel having a grit size of about -150 mesh, and thereafter finishing the surface of the roll with an abrasive block held against the surface of the roll and oscillating on a path parallel to the axis of rotation of the roll, the abrasive of said block having a grit size of about 800 mesh, whereby to produce a roll surface freeof directionality and characterized by a roughness of from about 4 to about 10 microinches R.M.S.

References Cited by the Examiner UNITED STATES PATENTS LESTER M. SWINGLE, Primary Examiner.

J SPENCE OVERHOLSER, Examiner. L. J. SHECHTER, Assistant Examiner. 

1. THE METHOD OF REFINISHING THE SURFACE OF A STEEL WORK ROLL WHILE THE ROLL IS BEING ROTATED ABOUT ITS AXIS OF ROTATION COMPRISING, THE STEPS OF GRINDING THE SURFACE OF SAID ROLL WITH AN ABRASIVE WHEEL HAVING A GRIT SIZE OF FROM ABOUT -80 MESH TO ABOUT -800 MESH, AND THEREAFTER FINISHING THE SURFACE OF THE ROLL WITH AN ABRASIVE BLOCK HELD AGAINST THE SURFACE OF THE ROLL AND OSCILLATING ON A PATH PARALLEL TO THE AXIS OF ROTATION OF THE ROLL, THE ABRASIVE OF SAID BLOCK HAVING A GRIT SIZE OF FROM ABOUT -600 MESH TO ABOUT -800 MESH, WHEREBY TO PRODUCE A ROLL SURFACE FREE OF DIRECTIONALITY AND CHARACTERIZED BY A ROUGHNESS OF FROM ABOUT 4 TO ABOUT 10 MICROINCHES R.M.S. 